Peripheral blood involvement is common in non-Hodgkin's lymphoma, and is probably related to early dissemination of disease and relapse following therapy. The aim of this proposal is to study the biologic relationship between malignant lymphoma cells present in tissues and in the peripheral blood. Specifically, we will compare circulating (migratory phase) and tissue (stationary phase) lymphoma cells with regard to features related to cell differentiation and localization, namely: (1) qualitative and quantitative expression of surface markers, (2) lectin binding (peanut agglutinin receptors), and (3) DNA content. We are especially interested in whether modulation of the cell surface accompanies entry of lymphoma cells into the peripheral blood and whether certain phenotypes are associated with increased risk of blood involvement. We will focus our attention to cell surface features that are related not only to lymphocyte differentiation, but which are expressed normally only in specific tissue sites, such as follicular centers. The preservation of tumor-associated antigens not normally present on peripheral blood lymphocytes could serve as new sensitive markers for circulating lymphoma cells. Quantitative DNA analysis will provide a comparison of the mitotic activity of migratory and stationary lymphoma cells, as well as detection of aneuploidy. The clinical significance of these features with regard to pathologic diagnosis, stage of disease, and response to therapy will be evaluated. In vitro studies will be directed at understanding the effect of differentiation or activation on lectin binding by lymphocytes. In order to perform these studies, we will take advantage of our ability to identify small numbers of lymphoma cells by a sensitive cytofluometric technique, "kapplambda analysis." This method will be combined with two-color cytofluorometry to specifically identify features of malignant lymphoid cells, including differentiation markers, lectin binding, and DNA content. Immunoperoxidase studies on tissues will corroborate the cytofluorometric data and will allow tissue localization of surface marker expression. This approach to identifying and analyzing malignant lymphoid cells will provide new insight into the biologic and clinical significance of peripheral blood involvement by lymphoma.